Method of and means for producing electrically-charged particles.



R. H.-GODDARD.

METHOD OF AND MEANS FOR PRODUCING ELECTRICALLY CHARGED PARTICLES. APPLICATION FILED APR.26, 1913.

13.32 964. Patented May 4, 19 15.

Witmaaoa %M A4 W404 7 UNITED STATES PATENT OFFICE.

ROBERT n. GODDARD, or WORCESTER, masssacnusm'rs. METHOD or AND nuns roa raonucme DLEcrnIcALLY-cHAReED narrows;

Specification of Letters Patent.

Patented May 4, 1915.

Application filed April 26, 1913. Serial No. 763,934.

To all whom it may concern Be it known that I, ROBERT H. GODDARD, a citizen of the United States, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented certain new and useful Improvements in Methods of and Means for Producing Electrically-Charged Particles, of which the following is a specification.

.The object of this invention is to produce electrically charged particles in a partial vacuum, by means of impact with particles which are themselves charged with electricity, and to employ this for useful purposes hereinafter more particularly pointed out.

I accomplish the object of my invention by causing a stream of particles which are charged with electricity to travel in a limited space by means of a suitable electrostatic or electromagnetic field, or a combination of these, and causing these charged particles to strike molecules of gas or vapor and render them charged with electricity.

In order to more fully describe my invention, reference will be had to the accompanying drawings in which,

Figure 1, is a diagram illustrating the method of confining the path of the charged particles by a magnetic field; Fig. 2, a semidiagrammatic sectional view illustrating the method of confining the charged particles by an electrostatic field; Figs. 3 and 4, vertical central sections taken on planes 90 apart, of a form of apparatus embodying my invention in which both magnetic and electrostatic means are employed for confining the path of the rays of charged particles; Figs.- 5 and 6, are vertical sectional views taken on planes 90 apart, of a modified form of the apparatus shown in Figs. 3 and 4; Fig. 7, a perspective view, and Fig. 8, an enlarged detail crosssection illustrating another modification of my said invention.

Referring to Fig. 1, N S represents a bar magnet symmetrical about axis OO, and the curved lines represent the lines of force of this magnet. Now if a beam of particles charged with electricity be directed suiliciently perpendicular to a radius from the axis O-O; that is, sufliciently perpendicular to the plane of the paper, these charged particles, indicated by the letter P, will move around the axis OO in circles indicated by the dotted lines, and the force on each of these particles is perpendicular to the lines of magnetic force, as indicated by the arrows. Thismerely indicates one way of confining the path of the charged particles, which in turn affects the charging of' the other particles. The same result may be effected by an electrostatic field, and one way of accomplishing this is shown in Fig. 2, where M represents a charged sphere, and M an oppositely charged hollow cylinder. If the beam of charged particles nearly perpendicular to a radius from the axis 0, these charged particles will move in circles indicated by the dotted lines. The electrostatic field, however, must be symmetrical about the axis ()O- In Figs. 1 and 2 the particles are taken as tively.

The beam of charged particles is most readily kept within a limited space by a combination of electrostatic and magnetic fields, and one form of apparatus embodying such an arrangement is shown in Figs. 3' and 4, to which reference will now be had. This apparatus comprises a tube T, in which is a cathode K and an anode A, the cathode being protected by glass, except at its face, as shown most clearly in Fig. 4, and magnet poles N S. The stream of electrified particles is, in this case, cathode rays. Ordinarily a stream of such rays proceeds nearly perpendicularly to the cathode, but in the present apparatus, under the influence of a strong enough magnetic field produlced by poles N S, these rays are deflected and proceed in spirals, the path of one ofwhich is indicated by the spiral dotted line C.

In order to prevent the rays from striking the walls of the tube T, two negatively charged metal disks P and P are placed near the sides of the tube as shown. A convenient way to charge disks P, and P is to connect them by wires W, to the cathode K. When the cathode rays approach the sides of the tube they are repelled by these charged P is sufliciently charged negaof the apparatus shown in and4, is shown in Figs.'5 and ,6, to-

l which reference will now be had. This a paratus also employs combined. electrostatic and magneticfields for confining the rays, and operates in the same way as the appa- "rams; of Figsg? and 4, the only diiference being in the .modified form of the several ia g'ring; thelcharged plates P and I are also of ring, form to conform to the tube T,

parts. a

In Figs. .5 and 6, tube T is in the form of 8nd themagnets N S are also in the form of T. TI-The magnets-in the case shown in Figs. and 6, however, have their inside pole faces so shaped as to give a stronger-field at the 7 part of-the gap nearest the axis OO, this being advisable to'insur'e the. particles from the cathode. K always passin below the cathode after once being sent'o It is not necessary '.to produce the beam by-any particular. cathode. For example, a

Wehnelt cathode,I'mercury 'cathode, or any other kind of "cathode, o r-'a plate caused to give oif rays by being illuminated, may be i used. Also, the: charged particles need not necessarilyberestrictedto cathode rays "the "so-called positive rays,f for example, or any other typeofcharged particles maybe employed.

Referring now to the form of the invem.

,tionfsh own-in Figs; 7 and 8, the tube T here is also in the form-of a hollow ring, but the magnetic. field isproduced by a winding W. W,,o n this ring. The rays proceedfrom a catho'de K in this case, as'in those'above described, but a-Ima'gnetN Sis necessary to v I piushthepath of the rays, upward in the im- I the path of the rays indicated by the-dotted mediate vicinity of the cathode, otherwise line in Fig. 8 would proceed in a circle directly from'thecathode, and would strike the back of the. cathode somewhere around "thepointQ.- a

Among the uses to which this invention may be put, may'bementioned the pumping Lticles. Isaac k isobtained This'fc p out of a tubeor other inclosed' space. It is -well known that when an electrical discharge takes'place in a vacuum tube, gases maybe-absorbed by the electrodes oreven by the walls of the tube itself, but all cases ng ert'.

b" a "1' tothefact the exhaustion ceases hat the gas in 9h ceasesto become ionized. In'qfac asibeen" hown that, in veryv high 'nduction takes place entirelysby the athode ray parescrib d;"with a Wehnelt cathode,"-ionizat 0i takes'lplace within the space B at any degreejof exhaustion, and the gas within thisspace is thus ionized and driven into an electrode, preferably charcoal, however high the vacuum may be. In this way a much higher degree of vacuum two rings lying on opposite sides ofthe tube.

. appearing'inth tube ain vacuum...

ample, would contain a suitable gas or va 3 por, the molecules of which would produce the illumination by impact with the charged particles travelingas described.

Another application of the said invention gage for high vacua; Owing to the impossibility of the charged particles-leaving the space B, Figs; 3 to 6, for example, until they have collided with atoms or molecules of the gas, they will travel a great distance before leaving this space, if the. vacuum is ex trem'ely highv Hence, if a'beam of rays is allowed to enter thespace for an instant, carrying a charge'of knewn quantity, the

is the production of a very sensitive vacuum i quantityof-electricity within space B will therefore slowly diminish; If the, ions escaping from spacexB arecarriedofi' as fast as they escape,=then aft the ma netic the degreeof-exhaustion'. 1

f I am aware .-that could. move in a" ici' g a uniform magne lqfifil'di provide projected exactlyatfrightang "netic lines of fo'rce,l'and provided-that there were no electrostatic effects p'rfesentg;

lei ion or *electronasdesiredin d: i W l' er? a; certain time, if n removed,- the 1 charge give'a'r' measure of inc turbitsmotion. Iarn also aware that a -sin gle ion or electron couldmove a circle as long as desired about an'infinitely long electrode by applying a suitable magnetic field, provided it wereprojected exactly at right angles to the axis of the said electrode, and provided that there were no electrostatic effects present to disturb its motion. I am] further aware that these hypothetical cases have been treated mathematically, owing to their simplicity. Nevertheless, they are not T within the scope of my invention, for the reason that they-are not realizable experimentally, and hence cannot be usedto pro duce the useful, results enumerated in my specification. The two said cases cannot be realized experimentally for the following reasons; first, a vacuum tube of infinite dimensions cannot bemade; second, in. a vacuum tube of finite dimensions there are always present electrostatic forces between the charged particles and the various electrodes, the walls of the tube, and even bodies 'outside the tube, each of which forces tends tochange the paths of the said particles;

and third, it is practically impossible to project a charged particle in a certain direction, with perfect precision. Furthermore, with a number of ions or electrons, instead of a quate means are employed to preventthe spreading of the group of particles, under the disturbing influences unavoidably present. In order to prevent the said spreading of the particles, the means described in this specification must be employed; namely, a magnetic field or an electrostatic field, of such'a shape that the field will overcome lateral spreading, illustrated by Figs. 1 and 2, respectively; or, second, means whereby the lateral spreading is overcome by charged plates, illustrated in Figs. 3, 4, 5 and 6; or, third, means whereby the lateral spreading causes the particles to describe closed paths ofdfinite magnitude, illustrated in Figs. 7 an 8.

Having thus described my invention, it should be understood that other modifications of the same may be made without departing from the spirit thereof.

What I claim is 1. The method of producing electrically charged particles by impact with other charged particles which consists in causing electrified particles to move continuously within a confined space and retaining all of them therein until they strike molecules or particles of gas or vapor.

2. Apparatus of the class described, comprising means to generate rays of charged particles and means to produce a field of energy acting on said charged particles to confine their entire movement to a limited space and a receptacle containing a gas or vapor the molecules of which are subject to impact by said charged particles.

3. Apparatus of the class described, comprising means to generate rays of electrically charged particles, combined electromagnetic and electrostatic means to produce a field of energy acting on said charged particles to confine them to a limited space, and a re- .ceptacle containing a .qas or vapor the molecules of which are subject to impact by said charged particles.

4. Apparatus of the class described, comprising a receptacle containing a gas or vapor, means to generate therein electrically charged particles, and means to confine said particles to a limited space within said receptacle and prevent any of them from passing outside of said space without first striking one or more molecules of said gas or vapor. I

5. Apparatus of the class described, comprising a tube containing a gas or "apor, a cathode, plates charged from the cathode, and magnet poles cooperating with said plates to confine the rays from said cathode to a limited space.

In testimony whereof I alfix my signature in presence of two witnesses.

ROBERT H. GODDARD.

Witnesses:

FRANCOIS W. HIXON, WILLIAM 0. W001). 

